Johnathan has been on a diet since january 2013 . so far , he has been losing weight at a steady rate . based on monthly weigh-ins , his weight , w , can be modeled by the function w=-3m+205 where m is the number of months after january 2013 .
a)how much did johnathan weigh at the start of the diet ?
b)how much weight has johnathan been losing each month ?
c)how many months did it take johnathan to lose 45 pounds ?